Tuning CO<sub>2</sub> Capture and Conversion with Metal–Organic Frameworks Crystallized in Aqueous Graphene Oxide Suspensions
Francisco G. Cirujano, Nuria Martín, Elena López‐Maya, Mayra G. Álvarez, M. Jesús Sánchez-Montero, Eduardo García‐Verdugo, María Dolores Merchán Moreno, M. Mercedes Velázquez
Abstract
We present a green procedure for the synthesis of metal–organic frameworks (MOFs) (having Zn, Ni, or Co) in graphene oxide aqueous suspensions (obtained with graphitized or nongraphitized carbon nanofibers) avoiding organic solvents and high temperatures. The materials were thoroughly characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), N 2 /CO 2 -physisorption, Raman and X-ray photoelectron (XPS) spectroscopies. The results demonstrate that the nature of the metal (electronegativity) and graphene oxide (defects of oxygen-containing groups) are key in the size, porosity, and defectivity (free noncoordinated linkers and open metal sites) of the MOF and significantly affect their CO 2 adsorption energy (up to 6 kJ·mol –1 increase), uptake (up to 5·mmol CO2 ·g –1 increase), and catalytic activity (up to 35% rate increase) with respect to bulk MOFs in the solvent-free, ambient pressure CO 2 cycloaddition to epoxides.